In order to install the Facebook button, I first set up a page for my new forum using the "Pages" feature on Facebook. You do this through your main Facebook account. From there, it will walk you through selecting the look of the box and provide you with the code (I had to tweak my code as it didn't come out right).

I also went to Twitter and picked up a code from the account there. Then I created a sidebar widget on my forum and pasted the codes there. You can follow the link under my profile to the right if you want to see how it came out. :-)

Then go to Widgets management in Modules. Create a widget and add the code. Scroll down to 'addition/deletion of personal widgets'. Click on the drop down menu, click facebook and add the widget. Job done.